package com.lujian.casual.benchmark;

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;
import org.openjdk.jmh.infra.Blackhole;
import org.openjdk.jmh.runner.Runner;
import org.openjdk.jmh.runner.RunnerException;
import org.openjdk.jmh.runner.options.Options;
import org.openjdk.jmh.runner.options.OptionsBuilder;

import java.util.concurrent.TimeUnit;


@BenchmarkMode(Mode.AverageTime)
@OutputTimeUnit(TimeUnit.NANOSECONDS)
public class BenchMarkConsumeCPU {


    /*
     * At times you require the test to burn some of the cycles doing nothing.
     * In many cases, you *do* want to burn the cycles instead of waiting.
     *
     * For these occasions, we have the infrastructure support. Blackholes
     * can not only consume the values, but also the time! Run this test
     * to get familiar with this part of JMH.
     *
     * (Note we use static method because most of the use cases are deep
     * within the testing code, and propagating blackholes is tedious).
     */

        @Benchmark
        public void consume_0000() {
            Blackhole.consumeCPU(0);
        }

        @Benchmark
        public void consume_0001() {
            Blackhole.consumeCPU(1);
        }

        @Benchmark
        public void consume_0002() {
            Blackhole.consumeCPU(2);
        }

        @Benchmark
        public void consume_0004() {
            Blackhole.consumeCPU(4);
        }

        @Benchmark
        public void consume_0008() {
            Blackhole.consumeCPU(8);
        }

        @Benchmark
        public void consume_0016() {
            Blackhole.consumeCPU(16);
        }

        @Benchmark
        public void consume_0032() {
            Blackhole.consumeCPU(32);
        }

        @Benchmark
        public void consume_0064() {
            Blackhole.consumeCPU(64);
        }

        @Benchmark
        public void consume_0128() {
            Blackhole.consumeCPU(128);
        }

        @Benchmark
        public void consume_0256() {
            Blackhole.consumeCPU(256);
        }

        @Benchmark
        public void consume_0512() {
            Blackhole.consumeCPU(512);
        }

        @Benchmark
        public void consume_1024() {
            Blackhole.consumeCPU(1024);
        }

    /*
     * ============================== HOW TO RUN THIS TEST: ====================================
     *
     * Note the single token is just a few cycles, and the more tokens
     * you request, then more work is spent (almost linearly)
     *
     * You can run this test:
     *
     * a) Via the command line:
     *    $ mvn clean install
     *    $ java -jar target/benchmarks.jar JMHSample_21 -w 1 -i 5 -f 1
     *
     * b) Via the Java API:
     *    (see the JMH homepage for possible caveats when running from IDE:
     *      http://openjdk.java.net/projects/code-tools/jmh/)
     */

        public static void main(String[] args) throws RunnerException {
            Options opt = new OptionsBuilder()
                    .include(BenchMarkConsumeCPU.class.getSimpleName())
                    .warmupIterations(1)
                    .measurementIterations(5)
                    .forks(1)
                    .build();

            new Runner(opt).run();
        }

}
